Amongst the genus Oreotrochilus, the White-sided Hillstar has the largest geographical range. It is found southern Bolivia as far south as southern Argentina, and at altitudes between at least 1200 and 4000 m, and sometimes as high as the snowline. Despite its hardy nature, at least some apparently depart Chile in the austral winter. In terms of plumage, the White-sided Hillstar is generally very similar to the Andean Hillstar (Oreotrochilus estella), with which the present species forms a superspecies, being largely bronzy-green above and white below, with a green throat in males, and a gray-spotted throat in females. Both sexes show extensive white in the otherwise dark tail.